Traditionally, a network is controlled at each of the Open Systems Interconnection (OSI) layers. The OSI model is a logical structure for network operations standardized by the International Standards Organization (ISO). The OSI model organizes the communications process into seven different categories and places the categories into a layered sequence based upon their relationships to other processes. Layers seven through four deal with end-to-end communications between a message source and a message destination, while layers three through one deal with network access. The layers communicate with their peers in the network. For example, at layer 0, optics can be populated with specific wavelengths. In some automated systems, optics can be programmed with certain characteristics, such as wavelengths, filters, and optical switching capabilities at the optical layer. Typically, these are all controlled by an Element Management System (EMS), Network Management System (NMS), or Operations Support System (OSS). For example, at layer 1, the network is typically based on a Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) standard, offering virtual Time Division Multiplexing (TDM) and data channels within the bit streams. The channels are built, switched, or dismantled at nodes. Again, this is typically controlled by the EMS, NMS, or OSS, although, more recently, layer-specific resource control protocols, such as Resource Reservation Protocol (RSVP), have been defined to control the network (reference Generalized Multi-Protocol Label Switching (GMPLS)). For example, at layer 2, a common protocol is Ethernet. Ethernet networks can be provisioned as in Provider Backbone Transport (PBT) networks (http://www.ieee802.org/1/files/public/docs2005/ah-bottorff-pbt-for-iee-v41-0905.pdf or http://www.ietf.org/internet-drafts/draft-allan-pw-o-pbt-00.txt). However, Ethernet networks typically provision simply by using the broadcast mechanism that is inherent in Ethernet. Optimizations have been added to extend reach and efficiency, such as bridges and multi-link bonding, which has added to the complexity of the protocols used, without changing the basic principles. For example, at layer 3, the Internet Protocol (IP) layer, IP routing is used to interconnect nodes in a network. Typically, these nodes all run routing protocols, such as Routing Information Protocol (RIP), Open Shortest Path First (OSPF) protocol, etc. Modern networks often apply key mechanisms, such as Multi-Protocol Label Switching (MPLS), at this layer in order to enhance the scalability of, add features to, or increase the stability of the networks. For example, at layer 4, data transport reliability, service ports, and the like are addressed. For example, at layer 5, the session layer, SIP can be used to initiate sessions. A session is a communication of some form between two peer entities. A relevant example is the initiation of a voice call from a wireless (WiFi)-enabled Personal Digital Assistant (PDA). The WiFi-enabled PDA generates the voice call to another user in a form such as “INVITE name@yourisp.com” using SIP. SIP agents track “name” and are aware of many items, such as, but not limited to, the location of “name” (e.g. “name” is now in “city”), the presence/availability of “name” (e.g. “name” can only be contacted by “family” at this time), and the media of “name” (e.g. “name” has set up the network to forward voice calls to a home voicemail at this time).
Current efforts to define protocols for optical networking have focused on layer-specific controls. Disadvantageously, layer-specific controls require accessing each layer to set up resources and/or services across the network. For example, for layer 0, protocol definition has focused on the specification of the wavelength to be used for a connection, the level of optical impairments that are allowed in the connection, and the source and destination within the optical network. Additionally, for layer 1, protocol definition has focused on the specification of the timeslot to be used for a connection within a TDM signal, the type of links to be used in the sense of any automated protection functionality associated with the links, etc. This work has been defined in the Internet Engineering Task Force (IETF) standards, such as Request for Comments (RFC) 3471, the GMPLS signaling functional description; RFC 3473, the GMPLS signaling extensions to RSVP; and RFC 3946, the GMPLS extensions for SONET/SDH control.
User Controlled Light Paths (UCLP) is a distributed network control application developed to support the sharing of network facilities amongst a community of users. This sharing is achieved by providing a software object model of the explicit set of available resources comprising the physical network segments and cross-connect equipment, with supported methods for provisioning and control of these resources. The users of the application interact with these UCLP objects to concatenate segments and cross-connects and assemble path objects that model services in the network. UCLP is disadvantageous in similar ways to other layer-specific signaling for network control. This mode of directly and explicitly manipulating models of the physical equipment and facilities to create service-desired topologies has limitations, as it necessarily exposes details of the underlying network infrastructure. Understanding and correctly interacting with these details can be a burden to users simply seeking service. Revealing network design and operational state at this level of detail is commercially undesirable for many service providers. UCLP is built on a web services framework provided by the Extensible Markup Language (XML)-based Simple Object Access Protocol (SOAP). The UCLP application interacts with the various existing configuration control interfaces (typically TL1 or SNMP) of the underlying physical network elements to establish services.
What has not been fully explored, however, is the area of technology-independent control that is required to offer services over a particular layer network. This is termed “call control” in the related standards (especially Automatically Switched Optical Network (ASON) or International Telecommunications Union (ITU-T) Recommendation G.8080 and is currently embodied in protocols only as a common identifier that links together signaling for multiple connections, or as a connection-independent control plane flow for purposes such as pre-connection compatibility verification. The former is described in ITU-T Recommendation G.7713.2, the specification for Distributed Call/Connection Management Using GMPLS RSVP-TE, while the latter is described in IETF draft “draft-ietf-ccamp-gmpls-rsvp-te-call-00.txt,” a work in progress.